SmartTube is a free and open-source YouTube client for Android TV and TV boxes. It removes ads, supports SponsorBlock, works without Google Services, and is designed for large screens and remote controls.
Note: the developer recently disclosed a build environment compromise and has since rotated keys, rebuilt the environment, and added additional verification steps. Users should update to the latest version and verify sources. GitHub: https://github.com/yuliskov/SmartTube
Helpfully, the app displays updates in-app when they become available.